Method Prep:15min › Extra time:4hr chilling › Ready in:4hr15min
Combine together the butter, the biscuits and 2 tablespoons of condensed milk. Press the mixture over the base and up the sides of a 20cm (8 in) plain flan ring placed on a flat plate. Leave in the fridge.
Pour the remaining condensed milk into a bowl, and the lemon zest and juice. Beat well. Leave for a few minutes to thicken, then fold in the cream. Pour on top of the biscuit base in the flan ring and smooth the top with a palette knife.
Leave in the fridge for a few hours to set.
Optionally, decorate the top with chocolate sprinkles or shavings just before serving.
The longer it is in the fridge, the better. If you can make it the day before it is needed, I would recommend doing that. To preserve any left , store in an air tight container in the fridge